[RFC PATCH v1 1/9] landlock: Refactor current_check_access_socket() access right check

[Mikhail Ivanov]

The current_check_access_socket() function contains a set of address
validation checks for bind(2) and connect(2) hooks. Separate them from
an actual port access right checking. It is required for the (future)
hooks that do not perform address validation.

Signed-off-by: Mikhail Ivanov <ivanov.mikhail1 at huawei-partners.com>
---
 security/landlock/net.c | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/security/landlock/net.c b/security/landlock/net.c
index c8bcd29bde09..669ba260342f 100644
--- a/security/landlock/net.c
+++ b/security/landlock/net.c
@@ -2,7 +2,7 @@
 /*
  * Landlock LSM - Network management and hooks
  *
- * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
+ * Copyright © 2022-2024 Huawei Tech. Co., Ltd.
  * Copyright © 2022-2023 Microsoft Corporation
  */
 
@@ -61,17 +61,34 @@ static const struct landlock_ruleset *get_current_net_domain(void)
 	return dom;
 }
 
-static int current_check_access_socket(struct socket *const sock,
-				       struct sockaddr *const address,
-				       const int addrlen,
-				       access_mask_t access_request)
+static int check_access_socket(const struct landlock_ruleset *const dom,
+			       __be16 port, access_mask_t access_request)
 {
-	__be16 port;
 	layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {};
 	const struct landlock_rule *rule;
 	struct landlock_id id = {
 		.type = LANDLOCK_KEY_NET_PORT,
 	};
+
+	id.key.data = (__force uintptr_t)port;
+	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
+
+	rule = landlock_find_rule(dom, id);
+	access_request = landlock_init_layer_masks(
+		dom, access_request, &layer_masks, LANDLOCK_KEY_NET_PORT);
+	if (landlock_unmask_layers(rule, access_request, &layer_masks,
+				   ARRAY_SIZE(layer_masks)))
+		return 0;
+
+	return -EACCES;
+}
+
+static int current_check_access_socket(struct socket *const sock,
+				       struct sockaddr *const address,
+				       const int addrlen,
+				       access_mask_t access_request)
+{
+	__be16 port;
 	const struct landlock_ruleset *const dom = get_current_net_domain();
 
 	if (!dom)
@@ -159,17 +176,7 @@ static int current_check_access_socket(struct socket *const sock,
 			return -EINVAL;
 	}
 
-	id.key.data = (__force uintptr_t)port;
-	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
-
-	rule = landlock_find_rule(dom, id);
-	access_request = landlock_init_layer_masks(
-		dom, access_request, &layer_masks, LANDLOCK_KEY_NET_PORT);
-	if (landlock_unmask_layers(rule, access_request, &layer_masks,
-				   ARRAY_SIZE(layer_masks)))
-		return 0;
-
-	return -EACCES;
+	return check_access_socket(dom, port, access_request);
 }
 
 static int hook_socket_bind(struct socket *const sock,
-- 
2.34.1